Sorry I've had reservations considering the issues Richard Barrington (an EE) had in assembly. I'm a lowly systems integrator and had no chance of maintaining a VEMS system in probably the most abusive motorsport in the world (off road racing). As such I've purchased yet another "Link Electro" product and am still developing Java apps for it. I'm still re-evaluating my EMS situation as the code is'nt open to modification and I can't activate my variable shock valving without creating a seperate controller, but I'll probably end up down the UMS path.
In regards to a software dyno, you probably want to get this integrated into whatever datalogging app VEMS currently has (JTune??) It's a simple bit of code that should be able to be written quickly. Displaying the results will take slightly longer.
Please cut and paste any section of this into a common page and let this orphaned page die!
Question from MembersPage/MarcelBlokpoel
Any progress with this? This is one feature I'd like to see. Been tinkering with software dyno for a while myself and have used it quite successfully. Might be able to help here. Comments and suggestions added below.
This program should be an applet included in the datalogging software. I intend to write it in Java and test on both CE and XP platforms.
I intend to implement this program in two phases. The first phase will simply be an RPM /Speed plot which will give those of us who are attempting to gain performance a start and will be quicker to implement than typing this page. Secondly will be a HP calibrated RPM /HP /Torque curve, just requires a little more input and code. Given the final drive ratio this program should also be able to calculate all gear ratios.
(How about a raw accel/time plot as a first stage? Accel being expressed in rpm/s or something. Should be easy to code and quite helpful for back to back before/after mod comparisons. Second stage would be an accurate estimate of power and torque curves based on MANY more parameters.)
Although probably not appropriate for a majority of the Genboard populous I plan on using two speed sensors. One on the driven wheels and one on the non driven set. These sensors will allow me to create a variable traction control system but will also give me the ability to meter wheel spin and hence have a more accurate measure of how much power is actually put to ground.
(Hmm, extra speed sensors and wheelspin detection are interesting but probably beyond the scope of many users. As a third and optional stage perhaps? It would be nice to have stage two independent of extra sensors, like most other software dynos. For stage three, perhaps ABS sensor signals (present on many cars already) could be tapped into. Also, 4x4's don't have non-driven wheels, but likely one wheel or pair will spin before the other unless you have stiff LSD's and snow or something.)
Taken from output from ECU.
Aerodynamic coeficient, frontal area
(without extra sensors, gear ratios are needed as well)
Must be able to be calculated from either saved data on ECU onboard datalogger or saved data from serial datastream.
Acceleration Force = weight 32.2 X acceleration in g's
Tire radius = ((Tire width X Aspect Ratio 25.4) + (wheel size 2)) 12
Acceleration Torque = Acceleration Force X Tire radius
Tire circumference = Tire radius X 2 X 3.14159265
Tire RPM = Car speed X 5280 3600 Tire circumference X 60
Rear Wheel Horsepower = Acceleration Torque X Tire RPM 5252
Peak HP and torque.